Hi Peter,
I am appreciative of your efforts in the ITU-T. To my knowledge no code changes have been made, hence my comment about no success. If there are new codes, please bring those to our attention.
Inadvertently your list illustrates why we have had such a hard time getting realistic specs for Ethernet. Excess caution freezes us in our tracks resulting in nothing getting done.
- We don’t care about old fiber in the field. Nobody runs 400GbE, or will run 800GbE or 1.6T over old fiber. If there is someone, somewhere who wants to do that, the answer is change
your fiber. If it’s too much trouble, maybe you shouldn’t be considering these speeds. Further, if someone has a specific use case for running these rates over really old fiber, they need to come into the Task Force and defend their application, otherwise
we end up with the tail wagging the Ethernet dog.
- We know the application space well, there is no mystery here. It’s the modern datacenter.
- The application space is not a 30 year old Telco Central Office.
- The proposal will be expanded to include both narrowing of ZDW and PDM.
- There is no broad market potential issue because there is no market for 800GbE and faster optics in shacks, sheds, and cabins.
- We are not creating a new fiber type; we are using realistic fiber parameters for deployed fiber.
Chris
From: Peter Stassar <000017da312dfb6f-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, October 18, 2022 6:05 AM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_B400G] Oct 2022 Session Unapproved Minutes Posted
Hi Chris,
Thanks for referring to the previous work that Pete Anslow and myself have undertaken in ITU-T SG15 to make the fiber specifications more in line with actual fibers in the field. You have been referring to that
work not having been successful.
Nevertheless I fully support (as you probably would expect) an in-depth investigation whether we can achieve more restrictive fiber specifications.
Concerns have been raised about the Lambda Zero, but also the PMD specifications.
However, I am also of the strong view that such an investigation will need to be carried out very carefully, because there are many questions to be answered, some of which are (non exhaustive list):
-
What are the actual characteristics (especially distributions) of modern G.652 B/D fibers, versus the characteristics of deployed fibers in the field, some of which may be pretty old.
-
What do we want and what do we need (will depend on the application).
-
How big is the application space? Mainstream of niche?
-
Which problem (space) will we be solving and which problem will we be creating.
-
Would it be sufficient to restrict Lambda Zero range? Or would we simultaneously need specific short reach PMD specs. Solving one problem may not be enough.
-
Are we creating a broad market potential issue by splitting the market in existing and new fibers.
-
Would we be effectively creating a new fiber type, e.g. G.652 E fiber, and what are the consequences of that.
So we should do this carefully, because it will have global effect on existing and new Telecom and Datacom networks.
Kind regards,
Peter
From: Chris Cole [mailto:chris.cole@xxxxxxxxxxxx]
Sent: Monday, October 17, 2022 6:22 PM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx
Subject: [802.3_B400G] Oct 2022 Session Unapproved Minutes Posted
Dear P802.3df TF Participants,
During last week’s meeting, Roberto presented actual
SMF Zero Dispersion Wavelength (ZDW) data collected by several manufacturers [ieee802.org].
ITU-T G.652 SMF codes, which underlie all 802.3 optical standards, specify ZDW from 1300nm to 1324nm. Looking at the above graph, the astute observer may ask why are we worried about 1300nm. The puzzlement is well justified. 1300nm ZDW
fiber basically doesn’t exist. It is not to be found in any datacenter. Yet all 802.3 standards use the ITU-T ZDW limits. In addition to unnecessarily burdening design, this also potentially significantly increases testing cost. To properly test, fiber with
1300nm and 1324 ZDW must be used. This requires going to manufacturers and asking for custom fiber which includes custom doping and other non-standard steps, which is not conducive to low cost.
This is rarely, if ever, done for real manufacturing environments. Instead, standard SMF is used. The result is that almost all transceivers in the field are not actually verified for wavelengths near ZDW, for example CWDM4 L2. As a practical
matter, this works out just fine, because the transceivers never encounter the full ZDW range. In other words, IEEE 802.3 pretends to write a serious spec, and industry pretends to test to it.
We have repeatedly tried to make the 802.3 SMF ZDW spec. realistic, for example:
https://www.ieee802.org/3/cu/public/May19/cole_3cu_01a_0519.pdf
[ieee802.org]
In each case, we have been instructed to go back to ITU-T and get the spec changed there. Because of a variety of reasons, some less than admirable, this has never been successful. A straightforward reason is that DWDM applications, which
are of primary interest in ITU-T, are in C-band where the exact value of ZDW doesn’t much matter. If you want to know the full story, please ask Peter Stassar who valiantly attempted numerous times to get this done.
As Baud rate goes up, this spec. becomes more important and we should base our optical specifications on realistic fiber parameters so that we don’t force manufacturers and users to wink and nod at each other that deployed optics meet specs.
We will be putting together a presentation to propose that we continue to use ITU-T G.652 SMF specs. but change ZDW for example to 1307nm to 1322nm, exact values TBDs. If you have interest in contributing please let me know. We are already
reaching out to fiber manufacturers.
Thank you
Chris
From: John D'Ambrosia <jdambrosia@xxxxxxxxx>
Sent: Thursday, October 13, 2022 3:31 PM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx
Subject: [802.3_B400G] Oct 2022 Session Unapproved Minutes Posted
All,
The unapproved minutes for the October 2022 session have been posted. Please see
https://www.ieee802.org/3/df/public/22_10/index.html [ieee802.org].
My thanks to Kent Lusted for his prompt turning around of minutes.
Please note that there were no additional changes made to the Oct 2022 Session Website.
Regards,
John D’Ambrosia
Chair, IEEE P802.3df Task Force
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